It is known of course to provide folding or retractable roofs for boats as well as for other vehicles The problem is more acute in boats, especially in certain recreational areas, because of the frequency with which low bridges are encountered. Consequently, the retracting structure must be convenient to operate. In addition to this, most boats, particularly those of the catamaran type, will include one or more upright structures; e.g., heads, galleys and the like, which normally rise to heights at about the level of the roof in its normal or operating mode. Thus, retracting of the roof alone is not enough to solve the low bridge problem, because of the stand-up head or galley. Hence, the basic feature of the present invention is to provide the upright structure of two-piece construction, including a base part carried by the boat and rising to an upper portion at about the level of the retracted roof and a top part hinged to the base part and so connected to the roof supports that the top structure retracts in unison with the roof and all basic high-level elements become low-level elements Further objects are to provide a simple design that may be provided as original equipment or added to existing boats and one that may be conveniently operated by the boat owner. Features and advantages other than those pointed out will appear as the disclosure of the invention proceeds.